1. Field of the Invention
The present invention relates generally to microchips useful as a micro total analysis system (μ-TAS) or the like suitably used for biochemical test of DNA, protein, cell, immunity, blood and the like, chemical synthesis and environmental analysis and the like, and particularly to microchips having a detection portion for optical measurement.
2. Description of the Background Art
In recent years in the fields of medical care, health, food, medicine development and the like it has been increasingly important to sense, detect or assay deoxyribo nucleic acid (DNA), enzymes, antigen, antibody, protein, viruses, cells and other similar biological substances and chemical substances, and there have been proposed a variety of biochips and micro chemical chips that can measure such substances conveniently. (Hereinafter such chips will be referred to as a “microchip” collectively.)
The microchip allows a series of test and analysis operations that are conducted in a laboratory to be conducted within a chip of a square measuring a few centimeters to 10 cm per side and having a thickness of approximately a few millimeters to a few centimeters. It thus allows the test and analysis operations to be conducted with a small amount of specimen and reagent, at a reduced cost, and with quick response and high throughput, and thus has many advantages such as a test result obtained immediately at a site at which the specimen is obtained.
Normally, the microchip has a fluid circuit therein. The fluid circuit is configured mainly e.g., of a liquid reagent reservoir portion for reserving a liquid reagent to be mixed with or used to cause a reaction with a specimen (e.g., blood as an example thereof) or used to treat the specimen, a measurement portion for measuring the specimen, the liquid reagent and the like, a mixer portion for mixing the specimen and the liquid reagent together to obtain a liquid mixture thereof, a detection portion for analyzing and/or testing the obtained liquid mixture and other similar portions, and a small flow path (e.g., having a width of approximately a few hundreds μm) connecting these portions appropriately. For use, the microchip is mounted typically in a device (a centrifuge) that can apply centrifugal force thereto. The microchip with appropriately directed centrifugal force applied thereto allows a specimen and a liquid reagent to be measured in amount and mixed together to provide a liquid mixture thereof and the liquid mixture to be introduced into the detection portion and the like. (For example see Japanese Patent Laying-open No. 2007-017342 for an example of a microchip having a fluid circuit therein.)
The detection portion having the liquid mixture accommodated therein is for example exposed to light (for detection) to measure the liquid mixture in transmittance or subject it to similar optical measurement.